perfectBy davidon 2/20/2012

this is truly a set it and forget ato. just wish i had purchased it a lot sooner

Great productBy Frankon 2/1/2012

Frank would recommend this product to a friend

The build quality was very good ad the factory support has been great too. I will soon be adding another Tunze 3155 to one of my other tanks

About perfectBy Billon 1/31/2012

Bill would recommend this product to a friend

Well constructed with magnets that will hold it wherever you want. Works well in a RSM 130D.

Worth the extra cashBy JOELon 1/29/2012

JOEL would recommend this product to a friend

Although this product is one of the more expensive top-off systems, you have so much already invested that it is nice not to rely solely on float switches and flood your house. Worth the extra cash in my opinion.

Does the jobBy Aaronon 1/20/2012

Aaron would recommend this product to a friend

Overall it is a great product. I have not experienced any malfunctions and the holder for the float switch and eye is very convenient. It does what it is supposed to do. However, I do have a few complaints.

1) The pump automatically pumps about a cup of water each time the pump is turned off. That means, if you dose kalk with your ATO as I do and your APEX turn the pump off because the pH is too high, as soon as it turns back on it pumps more high pH into the tank. Not a good feature. I'm sure it's to maintain constant flow through the tubing after it has been resting, but a manual button for this would be better

2) When the ATO alarm goes off, the only way to turn it off is to power down the ATO. Which means when you turn it back on, AGAGIN, it pumps more water into your tank. A button for this would also be better.

3) Eh...I guess it could be a little more attractive. Kind of an ugly black box.

The ATO to getBy Jasonon 1/18/2012

Jason would recommend this product to a friend

Finally got around to setting this up yesterday and it was easy as cake. 5 minutes out of the box and rolling. Everything you need for easy, dependability, and redundancy - could not have asked for a better ATO. Must have.

ATOBy TUBBYon 1/16/2012

TUBBY would recommend this product to a friend

GOT THIS ATO A WHILE BACK, JUST WANTED TO TEST IT OUT BEFORE I POSTED A REVIEW..."IT'S A WINNER" LOVE THIS ATO UNIT. VERY ACCURATE - ALSO LOVE THE MAGNET DESIGN. I ALSO PURCHASE A SPARE PUMP, IN THIS HOBBY YOU NEVER KNOW WHATS GOING TO HAPPEN. AT LEAST WHEN IT DOES HAPPEN , I'LL HAVE A SPARE.

Makes topping off easyBy Richardon 12/28/2011

Richard would recommend this product to a friend

definitely worth getting easy to set up, keeps water level perfect, no problems

great product a must haveBy jameson 12/6/2011

james would recommend this product to a friend

the tunze osmolater is a must have for any lazy reefer lol, it keeps the salinity at a set point where you want it i love it & i got it for a cheap price on black friday..

PerfectBy Jose Manuelon 11/24/2011

Jose Manuel would recommend this product to a friend

Does the job perfectly. my water level is always constant, alarm has never gone off.

Great ATOBy Frankon 11/23/2011

Frank would recommend this product to a friend

Keeps the warter right where i want it. i just wish i would of got this one a long time ago

over allBy Roberton 10/31/2011

Robert would recommend this product to a friend

I was a little skeptical after the instructions stated that this pump was not meant to handle large tanks. Let’s just say the pump works fine for my 370 gal. I have the ATO dripping into the sump and don’t take long for the water level to stabilize. I love this product; it keeps my skimmer stable and saves me a numerous trips of dumping water in tank.

Best ATO on the Market!By Adamon 10/20/2011

Adam would recommend this product to a friend

This ATO has saved me from carrying heavy 5 Gal buckets back and forth across the house, and the two different sensor technologies give me a sense of security when it come to functioning properly and not becoming being stuck in the on position and overdosing kalk!

A quality top off unit.By Bobon 10/18/2011

Bob would recommend this product to a friend

I found this top off unit easy to set up and comes with everything you need(no extra pump or valve needed). I would highly suggest this product as the first choice. The only drawback I found is when installing the magnet sensor mount in the tank (instead of a sump) I found the trim along the top of the tank will stop the outer magnet from going as high up on the tank as I wanted but, the remedy is as easy as a clamp or tank silicone adhesive. I am using an old 5 gallon salt bucket for my top off water. I added a float valve and enough 1/4" line to reach the RO/DI system in the basement so I dont have to hall the top off water up 2 flights of stairs to fill the bucket. I installed a ball valve on this line and only turn it on when the bucket needs to be filled. Works great!

Some problems to begin with -- resolved nowBy ShawnCCon 9/28/2011

ShawnCC would recommend this product to a friend

I had some problems with this unit right off the bat...

Firstly, the pump didn't seem to be pumping anything. After several minutes of running (as evidenced by the whining noise), still no water was coming out. The ATO reservoir sits right beside the sump, so it only has to pump a few feet, and with about 14 inches of head. Finally, I primed the line using the age-old sucking technique, and from that point on it seems to be working.

The next, and bigger, problem was that the float switch, which is supposed to be the safety backup, was not working at all. Regardless of whether I lifted it manually or submerged it, no alarms would sound and the ATO kept pumping away. I contacted Roger at Tunze on their support forum at ReefCentral, and he confirmed that the magnets inside the float switch bracket were installed (by the factory) upside down. They are supposed to be at the bottom of the bracket, but these ones were at the top. Becuase the float switch itself operates on magnetic principles, the mis-aligned magnetic field was interfering with the switch, causing it to fail. After a botched attempt at fixing it myself, Roger is sending me a replacement bracket. No hassles--just a simple replacement.

The Osmolator and I still have yet to build a trust relationship. I've decided to plug it into one of my Apex controller's switched outlets, with yet another float switch (monitored by Apex). This way, the Apex can also kill the power to the top off if it detects levels getting too high. Redundancy is key.

The only other gripes I have with it, as other people have mentioned, are that it automatically runs the pump for several seconds when initially powered up (why?) and that the pump itself has a high-pitched shrill whiney sound to it, so it can easily be heard from outside the stand when it's running.

In general, after much manual testing of the optical eye sensor, I would say that it works quite well, and I am pleased with it. The price is hard to swallow, but I rent my apartment and it has hardwood floors, so I'm willing to take all precautions necessary to prevent overflow disasters.

Tunze customer service (Roger) has been very responsive, so in that regard, I give them (him) an A++.

perfectBy illyaon 7/10/2011

illya would recommend this product to a friend

This is a very nice ATO that keeps the level of water right where you want it. It saves me about 15 min a day at least from manually having to refill my sump, that's a lot of time saved after a while. well worth the cost, quality unit and you can tell a whole lot of thought went into this unit.

Only one flawBy Carolon 7/7/2011

Carol would recommend this product to a friend

Love this system but the only flaw is the pump does not last, after 3 months it starts to drips after pump is off and sometime its a non stop drip. I'm on my 3 pump now and the system is only 9 months old. But other than that its a great ATO sytem, I just keep a extra pump now.

Great productBy Craigon 7/2/2011

Craig would recommend this product to a friend

I just ordered my second Osmolator as the control module of my first one just died after 3 years. I didn't consider buying any other ATO system as this thing worked perfectly until it went out. The Osmolator is so precise at maintaining water level which is essential for growing healthy coral.

Awesome auto top off unit.By Dirtmanon 4/30/2011

Dirtman would recommend this product to a friend

I like to have my 90 gallon reef tank as full as possible so it took a little time to adjust the over flow shutoff switch to the correct level. Once the sensors were adjusted to the correct height it has worked flawlessly. I'm very pleased with the Tunze 3155 Osmolator. It's worth its weight in gold.

Good but flawsBy stevenon 4/11/2011

steven wouldn't recommend this product to a friend

This is a good product that works but has some flaws:

1. Every time the unit loses power or is unplugged and plugged in again, it will start pumping water for 10-15 seconds even if you are at the correct level or above.
2. There is an alarm to signial too much water. It's loud and can not be disabled unless you take the unit apart and move a jumper.
3. The eye didn't work correctly out of the box. I had to wet it and rub it with a clean cloth vigorously to get it to function. Once cleaned it worked. I question it's long term reliability.

Kinda wish I went with the JBJ ATO and saved 100 bucks.

excellent productBy bblinkson 4/9/2011

bblinks would recommend this product to a friend

Great product, set it and forget it. This product will make your life a lot easier.

Peace of MindBy Timon 3/27/2011

Tim would recommend this product to a friend

I purchased this product to go with a Kalk stirrer I recently purchased from BRS. I had watched the videos from the knowledgeable staff at BRS. I have to say this auto top off is the best thing I ever purchased for my system. It is extremely easy to set up and you don't have the worry of it over filling since it comes with multiple safety features.

Expensive, but awesome.By Allanon 3/25/2011

Allan would recommend this product to a friend

I was hesitant to buy this, given the premium price, but it keeps my sump level incredibly steady. MUCH better than the upside-down water cooler jug gravity feed setup I had before. The only odd thing about it is that it runs the pump for about 5 seconds or so any time you pull the plug and plug it back in. Not an issue unless you're turning it on and off a lot. Though that could happen if you have it on a controller set to only turn it on for say 5 minutes every hour. Just something to be aware of.

Worth the price ...By Larryon 3/14/2011

Larry would recommend this product to a friend

The Tunze osmolator is not the cheapest ATO, but I think it is the best. Worth the price for piece of mind.

Best money I ever spent!!By Steveon 2/2/2011

Steve would recommend this product to a friend

I cant say how many times I let my ro run into my tank to top it off and forgot about it.this is set it and forget it.I have the pump in a reservoir that has a float switch connected to my ro.Nothing better than having one less thing to do to your tank.Pump is loud though just so you know but the water level is extremely precise.

AwesomeBy Davidon 1/6/2011

David would recommend this product to a friend

After having a little trouble getting the osmolator working I emailed Tunze and washed the sensor with soapy water. This thing is awesome. I'm glad I spent the money and bought it over other float switches.

First in ClassBy Downbeachon 12/13/2010

Downbeach would recommend this product to a friend

Works flawlessly, set it and forget it.

Love it!By Geddyon 11/12/2010

Geddy would recommend this product to a friend

This is the best investment I have made in reef keeping. Works perfectly in my setup and has been running strong for 3 years plus. At the time I was worried about the cost but now I would not hesitate if I needed another for a second setup. The new magnet mount looks like a nice upgrade too.
A quick dip in vinegar every 3 months or so is the only maintenance I have ever done on the unit. You need to keep you outlet line above the storage tank BTW to avoid a siphon.

My favorite product By Johnon 9/27/2010

John would recommend this product to a friend

I don't know how many times I have come home to my sump pump running dry! No longer! I love not having to constantly check the water level in my sump. Product has exceeded my expectations and has yet to fail on me (not expecting it to).

Perfect!!!By Ferdinandon 8/10/2010

Ferdinand would recommend this product to a friend

Very easy set up and great product. Oh and make sure u clean the eye first before setting up. :)
And also the price should be on the $150 price range.

Best Investment Ever!!!By Davidon 7/2/2010

David would recommend this product to a friend

Hands down the best investment i,ve made in this hobby.This thing is dead accurate.Set it and forget it.Very easy to install ,easy to clean and very dependable.If you think the pump is loud just suspend it in the reservoir and you can barely hear it when it kicks on.Would recommend great product!

superb unitBy Davidon 5/19/2010

David would recommend this product to a friend

uses solid state sensor instead of float unit. does have a float unit as backup in case of primary sensor failure. has kept my sump level dead steady. pump initially had some noise but that went away after a few cycles and now is quiet. i did have an issue with some bubbles that collect on the sensor cause the unit to think the water level was low. fixing the bubble problem ended this problem.
seems like a lot of $ for an autotop off, but well worth it in my opinion.

Works very nicelyBy Dean Crafton 4/13/2010

Dean Craft would recommend this product to a friend

Peace of mind that leaving your system for a few days will not result in a major disaster. Found no problems in setup, and it seems to require little, if any, further tweaking. I like to keep my tank covered tightly to minimize evaporation. If you fail to do this you will be adding lots of makeup water to your topoff tank. The other advantage of a secure cover is that the jumpers such as warsses do not go "carpet surfing" as they are very prone to do.

The bestBy Ryanon 4/9/2010

Ryan would recommend this product to a friend

Only top off I will use. The electric eye is a billion times more reliable than a mechanical float switch.

Great ProductBy Davidon 2/16/2010

David would recommend this product to a friend

Really easy to set up. Make sure you clean the "eye". Makes it easier to adjust at first.

Outstanding!By Erikon 2/12/2010

Erik would recommend this product to a friend

One of the best purchases I have made for my reef. Makes life so much easier verses manual top offs and it is very reliable. The "eye" is accurate and it even has a float switch as a safety that will shut off the unit and activate a rather loud buzzer. I use a five gallon bucket of RODI water as a reservoir and it works great. If the bucket runs dry the pump will auto shut off after a few minutes to keep from burning itself up and again sound the alarm. I used the magnetic brackets to mount the eye and the "shut off" float a few inches higher up separately in my sump. One of the brackets is setup to hold both the sensor and float if that would suite your setup. The magnets are quite strong so you can be confident the "eye" isn't going to slide anywhere and change your sump level. One caution...I had an issue with it over filling my sump and setting off the buzzer the first few days. Couldn't figure out what was going on at first and then it hit me...and I felt foolish. This may seem like common sense but mind where you place the top off tube. I had tucked it down into the water next to my return pump to keep splashing noise down. Well...next to a full 5 gallon bucket full of RO water...once the pump started the siphon even after the pump cut off gravity continued to empty the bucket into my sump. So I shook my head and placed the tube a few inches from the top of the sump tank...above the water level in the bucket...problem solved.